Slip ring assembly



Nov. 29, 1966 J. E. SLACK 3,239,140

SLIP RING ASSEMBLY Filed Feb. 26, 1962 2 Sheets-Sheet 1 F9 2 .f izza. 3

INVENTOR. Jame? E. 5Zczc'k Nov. 29, 1966 J. E. SLACK SLIP RING ASSEMBLY2 Sheets-Sheet 2 Filed Feb. 26, 1962 INVENTOR. Ja mas Z la 0% UnitedStates Patent 3,289,140 SLIP RING ASEMBLY James E. Slack, Westchester,Ill, assignor to Borg-Warner Corporation, a corporation of IllinoisFiled Feb. 26, 1962, Ser. No. 176,869 2 Claims. (Cl. 339-) Thisinvention relates to current collecting and distribution devices andmore particularly to molded slip ring assemblies.

A number of problems have existed up to the present time in makingcurrent-collecting and distributing devices. For example, it has oftenbeen a problem to secure slip rings to insulation material in a mannersuch that they will not tear loose easily from the insulation material.Controlling the relative location of slip rings and conductor leadsother than those to which a particular slip ring is attached has alsoposed a problem. Difficulties have also been encountered where too largea number of parts have gone into slip ring assemblies. This has causedendless difficulty both in the original assembly and later in the actualoperation of the device.

One of the objects of this invention is to provide a unitary molded slipring assembly of simple inexpensive construction. Another object is toprovide such as assembly wherein each of the slip rings and itsrespective conductor lead is integral, that is, both the slip ring andconductor lead being formed from the same material. Thus, no operationis required to connect the conductor lead to the slip ring. A furtherobject is to eliminate the problem of loose parts.

Another object is to provide an assembly in which the construction issuch that contact between the conductor leads and either thenon-associated slip rings or the shaft upon which the slip ring assemblyis mounted will not occur.

Other objects and advantages will be apparent as the description ofcertain embodiments of the invention proceeds, taken in connection withthe accompanying drawings in which:

FIG. 1 is a view in elevation of one embodiment of a unitary molded slipring assembly;

FIG. 2 is a view in section of the slip ring of FIG. 1 taken along theline 22 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3--3 of FIG. 1;

FIG. 4 is an enlarged partial sectional view taken on line 44 of FIG. 1;

FIG. 5 is a plan view of a flat metal stamping from which the slip ringsand connector leads are made;

FIG. 6 is a perspective view of the stamping of FIG. 5 after conductorleads have been formed from the stamping;

FIG. 7 is a perspective view showing the stamping of FIG. 6 bent intoannular form;

FIG. 8 is an enlarged perspective of a portion of the stamping showing adovetail groove and rib pattern with projections formed in the grooveportion;

FIG. 9 is an enlarged perspective of a portion of the stamping showingan alternative construction with depressions formed in the grooveportion;

FIGS. 10-13 illustrate a second embodiment of the invention wherein aslip ring assembly has 3 slip rings.

Referring now to FIGS. 1-3, there is shown a unitary molded slip ringassembly 10 comprising slip rings 12 and 14 formed on molded insulationmaterial 16. The slip ring assembly 10 is adapted to be mounted on arotating shaft (not shown) so that an inner surface 18 of the moldedinsulation material will be in contact with said shaft. The assembly 1 0may be secured to the shaft by means of a key (not shown) and keyway 20,for

Patented Nov. 29, 1966 example. The slip rings 12 and 14 have formedthereon respectively conductor leads 24 and 22 by a method hereinafterto be described. It will be noted from FIG. 2 that the lead 24 isembedded within the molded material.

The method of making the unitary slip ring assembly will now bedescribe-d. Slip rings 12 and 14 are made from an electricallyconductive material such as copper, for example. Initially, a blank 25(see FIG. 5) is stamped from whatever kind of material which is to beused for the slip rings and conductor leads. This material has beenpreviously roll-formed to provide the dovetailed cross-section shown inFIG. 4. A pattern comprising ribs 26 and grooves 28 is formed in onesurface of the blank 25 in a longitudinal direction as shown in FIG. 5.During the forming of the grooves 28 small deformations such asprojections 30, or in the alternative, indentations 32 are formedtherein for a purpose to be hereinafter described. The tops of the ribs26 have been flattened to expand the metal sidewise into the adjacentgrooves 28 to leave a dovetailed cross-section as shown in FIGS. 8 and9. Thus, the sides 27 and 29 of a rib form acute angles a and b with thebottom of an adjacent groove 28. This is a continuously extendingdovetailed cross-section. Conductor leads 22 and 24 are then formed Ifrom the tabs 34 and 46 respectively. The end of the slip ring blank 25by the portion 38 and the lead 24 re mains connected to the slip ringblank by the portion 40, as seen in FIG. 6. It will be appreciated thatin offsetting the lead 24 from the blank 25, a shearing operation isnecessary, as Well as a bending operation to form the portion 40 atsubstantially right angles to the blank 25. A bending operation is alsonecessary to offset the lead 22 from the blank 25 as shown in FIG. 6.After all this is done the blank is ready for bending into the annularform 42 shown in FIG. 7.

It will be noted in FIG. 7 that the projecting portion 37 of the blank25 fits together with the portion of the blank 25 remaining after thelead 24 has been sheared therefrom.

After forming the blank 25 into the annular form 42, molded insulationmaterial is applied to the inside surface of the blank. The moldedmaterial may comprise, for example, a thermo-reactive phenolic resin incombination with a heat-resistant filler such as asbestos fiber, both ofthese items being commercially available. It will be appreciated thatthe lead 24 becomes firmly embedded in the molded material after thelatter has set.

When the assembly is ready for use, it is mounted, for example, on therotary member to which it is to be secured. A slight cut may be takenover the outer surface 44 to true this surface with respect to therotating member. It is at this juncture that the blank 24 in its annularform 42 is separated into the individual slip rings 12 and 14 by merelycutting groove 46 in the assembly and through the annular form. Thisleaves two separate slip rings 12 and 14 with their respectivelyintegral conductor leads 24 and 22.

It will also be noted that the slip rings 12 and 14 are tightly securedto the molded material by virtue of the dovetail arrangement asillustrated in FIG. 4. In addition, the projections 30 or in thealternative, the indentations 32, prevent relative rotary movementbetween the molded material and the slip rings.

A second embodiment of the invention is shown in FIGS. 11-13 wherein themolded slip ring assembly has three slip rings each having an integralconductor lead. A blank 48 is formed from electrically conductive mateona shaft or other rotary member.

rial in which has been impressed the same rib and groove pattern of FIG.5. By a shear forming operation two conductor leads 52 and 54 aresheared from the blank 48 and the three leads 50, 52, and 54 are offsetin the same direction from the plane of the blank 48 as shown in FIG.10. At the left end of the blank 48 as shown in FIG. portions aresheared therefrom so that when the blank is bent into the annular shellform of FIG. 11 the edges 56, 58, and 60 will substantially mate withthe edges 62, 64, and 66. Insulation material 16 is then molded on theinside of the annular shell 68 to form a molded assembly 70 having aninner surface 18 for positioning When positioned on such rotary membergrooves 72 and 74 are cut in the molded assembly 70 through theconductive material leaving insulated slip rings 76, 78, and 80 withtheir respectively attached conductor leads. A truing cut may be takenon the assembly 70 either before or after the grooves 72 and 74 are cuttherein. It will be appreciated that the slip ring assemblies having agreater number of slip rings and attached conductor leads may be formedin substantially the same manner by following the teaching herein.

It will be observed that these devices can be relatively simplymanufactured. In the slip ring assembly, for example, there are no looseparts, and contact of the conductor leads with either the shaft uponwhich the assembly is mounted or with a slip ring to which it is notattached is absolutely prevented. In the manufacture of the slip ringassembly, there are no complicated operations such, for example, asmatching up apertures in separate slip ring mountings designed toreceive conductor leads.

This integral construction of slip rings and conductor leads alsoeliminates the problem of lack of control in positioning the slip ringswith respect to the leads.

In addition, since the slip rings and leads are necessarily of the samematerial no differences of electrical potential can be set up to causedeterioration of the insulation material.

The dovetailed rib and groove pattern advantageously provides means forsolidly securing the slip rings in the molded material. In addition thedeformations made in the bottom of the grooves help to prevent relativecircumferential movement between the slip rings and the insulationmaterial.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto as many variations will be readily apparent to thoseskilled in the art, and the invention is to be given its broadestpossible interpretation within the terms of the following claims.

I claim:

1. A unitary molded slip ring assembly comprising a plurality ofsubstantially cylindrically shaped spacedapart circumferentiallyextending electrically conductive strips forming a plurality of slipring elements and defining a circumferentially extending annular groovebetween adjacent cylindrically shaped spaced-apart circumferentiallyextending strips, a substantially cylindrical core of molded insulatingmaterial circumscribed by and supporting each slip ring element andbeing provided with a peripheral surface portion defining a part of saidcircumferentially extending annular groove, each slip ring element beingprovided with an integral extension struck out and offset from saidstructure and extending radially inwardly and axially of a respectiveelement to define an integral conductor lead for a respective slip ringelement, each of said slip rings being provided with an internalcircumferential portion having plurality of alternating dove-tailed ribsand grooves, and said core having an outer circumferential portionhaving a plurality of alternating dove-tailed ribs and grooves incomplemental axially keyed locking relation with the ribs and grooves ofeach slip ring.

2. A unitary molded slip ring assembly comprising a plurality ofsubstantially cylindrically shaped spacedapart circumferentiallyextending electrically conductive strips forming a plurality of slipring elements and defining a circumferentially extending annular groovebetween adjacent cylindrically shaped spaced-apart circumferentiallyextending conductive strips, a substantially cylindrical core of moldedinsulating material circumsubscribed by and supporting each slip ringelement and being provided with a peripheral surface portion defining abottom portion of said circumferentially extending annular groove, eachslip ring element being provided with an integral extension struck outand offset from said structure and extending radially inwardly andaxially of a respective element to define an integral conductor lead fora respective slip ring element, each of said slip rings being providedwith an internal circumferential portion having plurality of alternatingdove-tailed ribs and grooves, said core having an outer circumferentialportion having a plurality of alternating dove-tailed ribs and groovesin complemental axially keyed locking relation with the ribs and groovesof each slip ring, and each of said grooves of the circumferentialportion of the slip rings including a bottom portion having a pluralityof deformations for preventing relative circumferential movement betweensaid slip rings and said core.

References Cited by the Examiner UNITED STATES PATENTS 383,509 5/1888Webster 29-193 922,990 5/1909 White 29-493 1,493,859 5/1924 Himes310-232 1,641,414 9/1927 Critchfield 29-15554 1,729,747 10/1929 Palm 29-149.5 1,870,236 8/1932 Chervenka 310 232 2,551,030 5/1951 Madden.

2,753,534 7/1956 Sprigg 339 -59 2,880,402 3/1959 Gardner 339 5 2,926,3262/1960 Boily et a1. 339-8 2,961,385 11/1960 McGall 204 15 2,985,7815/1961 Julian 310 232 3,014,193 12/1961 Schiller 339-8 3,066,386 12/1962Filipczak 29-1555 3,140,414 7/1964 Skjodt et a1. 310 235 EDWARD C.ALLEN, Primary Examiner.

JOSEPH D. SEERS, ALFRED S. TRASK, Examiners.

1. A UNITARY MOLDED SLIP RING ASSEMBLY COMPRISING A PLURALITY OFSUBSTANTIALLY CYLINDRICALLY SHAPED SPACEDAPART CIRCUMFERENTIALLYEXTENDING ELECTRICALLY CONDUCTIVE STRIPS FORMING A PLURALITY OF SLIPRING ELEMENTS AND DEFINING A CIRCUMFERENTIALLY EXTENDING ANNULAR GROOVEBETWEEN ADJACENT CYLINDRICALLY SHAPED SPACED-APART CIRCUMFERENTIALLYEXTENDING STRIPS, A SUBSTANTIALLY CYLINDRICAL CORE OR MOLDED INSULATINGMATERIAL CIRCUMSCRIBED BY AND SUPPORTING EACH SLIP RING ELEMENT ANDBEING PROVIDED WITH A PERIPHERAL SURFACE PORTION DEFINING A PART OF SAIDCIRCUMFERENTIALLY EXTENDING ANNULAR GROOVE, EACH SLIP RING ELEMENT BEINGPROVIDED WITH AN INTEGRAL EXTENSION STRUCK OUT AND OFFSET FROM SAIDSTRUCTURE AND EXTENDING RADIALLY INWARDLY AND AXIALLY OF A RESPECTIVEELEMENT TO DEFINE AN INTEGRAL CONDUCTOR LEAD FOR A RESPECTIVE SLIP RINGELEMENT, EACH OF SAID SLIP RINGS BEING PROVIDED WITH AN INTERNALCIRCUMFERENTIAL PORTION HAVING PLURALITY OF ALTERNATING DOVE-TAILED RIBSAND GROOVES, AND SAID CORE HAVING AN OUTER CIRCUMFERENTIAL PORTIONHAVING A PLURALITY OF ALTERNATING DOVE-TAILED RIBS AND GROOVES INCOMPLEMENTAL AXIALLY KEYED LOCKING RELATION WITH THE RIBS AND GROOVES OFEACH SLIP RING.